The Biostatistics Core will serve as a resource and collaborator for all projects related to this Program Project. In particular, the Biostatistics Core will consult on the statistical design of all projects and will consult on the application of appropriate statistical methodological techniques for all analyses. Staff of the Core will continue to be active collaborators in publications from this research. It will be responsible for collaboration in the design of all forms used, and will implement a data entry/data management procedures to achieve the most cost-effective computer utilization for the present and proposed studies. Methodologic developments will be pursued in constructing multivariate linear models for the cross-sectional/longitudinal data which are an important focus of the Program Project. New models for the spatial distribution of neuropathologic AD lesions will be developed in order to better understand the sampling errors characteristic of various protocols for quantifying AD markers.